The present invention relates to cordless electrical devices, more specifically, to soldering irons and soldering iron tips.
In many industries and for some hobbyists, it is necessary to manually make electrically conductive connections between various electrical components. In order to make such connections, a wide variety of soldering irons have been developed, for use in a variety of applications, ranging from repair of printed circuit boards, use in the telecommunications industry, and use in the manufacture and repair of heavy industrial electrical and electromechanical equipment. Existing soldering irons vary by power source, application, performance, shape, size, temperature, tip type, heat source, price, and portability.
Regardless of the size or capability of the soldering iron, existing soldering iron tips are generally categorized into two main types. The first consists of a heating element surrounded by a non-conductive film material, which is then covered by a thermally conductive metallic shell. The tip is heated by the application of electricity to the heating element. Depending on the application, the tip size can vary widely. The power source may also vary, ranging from 2.4 volt batteries through a 220 volt alternating current conventional outlet. Regardless of the power source, the flow of electricity to the heating element is typically controlled by a switch in the electrical circuit leading to the heating element. The switch is often a manual switch located on the outer case of the soldering iron.
An alternate soldering iron tip includes a solid tip of a thermally conductive material, usually a metal, which is heated by burning butane. Such soldering irons are typically portable, and the butane is supplied from a cartridge within the tool.
A number of problems exist with the current types of soldering irons. Soldering irons that must be plugged into a conventional electrical outlet lack mobility and are restrictive in use. Regardless of the tip type, the time generally required to reach soldering temperatures initially ranges from 10 to 60 seconds. If the soldering iron has not completely cooled down between uses, subsequent uses may not require as much startup time, but are still not immediate. Similarly, the time required for desired cooling can be substantial, posing the danger of burns to the operator and his or her surroundings after the tool has been removed from the work surface and before the tool has cooled. Furthermore, metal tips may become soldered to the connection, damaging the connection as the tip is removed and requiring further repair.
Existing cordless soldering irons resolve the mobility issues with soldering irons connected to conventional outlets, but at the cost of further problems. Butane irons require the operator to store and maintain a highly flammable gas and do not resolve the other deficiencies noted above. Existing battery-powered cordless soldering irons can typically make only 125 connections per full charge and are only capable of equivalent power output in the range of about 15-25 watts.
In order to ensure that the operator is able to adequately view the joint to be soldered, existing electric soldering irons are sometimes provided with a small lamp disposed on the soldering iron to illuminate the tip and connection. In these devices, the light is controlled by the same switch that controls the flow of electricity to the heating element. A disadvantage of this system is the inability to use the light without heating the tip of the soldering iron. This requires the operator to carry a separate flashlight if he or she wishes to illuminate the surroundings without soldering or heating.
As noted above, soldering irons are primarily used for making electrically conductive connections in various forms of electrical and electronic equipment. A visual inspection of the soldered connection may not always accurately determine whether or not the connection has been formed correctly and is now electrically conductive. Therefore, those operators who wish to test their connection, or to test electrical continuity between any two other points in the circuit, must carry a separate continuity tester.
Thus, a need exists for a soldering iron that can heat up and cool down quickly, minimizing the risk of burning the operator and/or his or her surroundings. Ideally, the soldering iron would be portable and could be used to form a large number of connections at high power output without having to be recharged. There is a further need for a portable soldering iron which can also be used as a flashlight and/or a continuity tester, reducing the number of tools to be carried by the operator to the site of the work.
Generally described, the present invention provides a soldering iron, with a graphite tip having two separate halves that are electrically isolated from one another. The tip halves are each electrically connected to the opposite sides of an electrical power source. When both halves of the tip are applied to an electrically conductive material, such as the material to be soldered, an electrical circuit between the tip halves and electrical power source is completed. The halves of the tip are constructed from material having high electrical resistivity and low thermal conductivity. Therefore, the tip can reach operating temperatures quickly. When the tip is removed from the joint, the electrical circuit is broken and the tip material quickly cools.
Because electricity is only able to flow when the two pieces of the tip are electrically connected, no separate switch is required. Furthermore, the soldering iron may be used without waiting for the tip to heat. The tip also reduces the risk of burning the operator and/or his or her surroundings because it heats up and cools down quickly. Furthermore, the tip material eliminates the risk of the tip becoming stuck in the joint. The tip material also permits higher power outputs than other known battery-operated portable soldering irons and permits over 300 joints for each full charge.
In accordance with further aspects of the present invention, in one embodiment, the soldering iron also includes a light disposed on the case to illuminate the tip and connection. The light is controlled by a separate switch and permits the tool to be used to illuminate the operator""s surroundings without actually having to heat the tip. This aspect of the invention permits the operator to avoid the necessity of carrying a separate light source when working or intending to work in areas without sufficient lighting.
In accordance with other aspects of the invention, another embodiment is provided in which the tool also includes an electrical lead connected in series with the lamp, the power source, and a continuity testing probe. This aspect of the invention permits the soldering iron to test circuit continuity by applying the lead and the probe directly to a newly soldered connection, or to another part of the circuit to be tested. This aspect of the invention permits the operator to avoid the necessity of carrying a separate continuity tester to perform this function.